To improve strategies for the early identification of individuals at a heightened risk for the development of psychosis, we investigated the relationships and interactions between 3 psychosis-proneness dimensions for the development of schizophrenia spectrum psychosis: schizotypy, basic symptoms and the ultra-high risk (UHR) criteria.Methods
Seventy-seven UHR individuals and 79 healthy controls were assessed for schizotypy and basic symptoms using self-report questionnaires at baseline. UHR participants were monthly assessed for conversion to psychosis over a mean period of 25.8 months.Results
Sixteen UHR participants (20.8%) converted to schizophrenia spectrum psychosis. In stepwise Cox regression, the interaction between basic symptoms and physical anhedonia was selected as a sole predictor of conversion in UHR participants, whereby the self-reported number of the 8 basic symptoms significantly increased the risk for conversion in those with pronounced physical anhedonia.Conclusion
Our findings suggest that questionnaire-assessed basic symptoms, irrespective of their predictive validity, may predict a psychotic breakdown in pre-identified UHR individuals who are with genetic vulnerability to schizophrenia. Including all 3 psychosis-proneness dimensions into prediction models might help establish a more valid pathogenetic model of schizophrenia, and moreover, may provide some clues about course alteration strategies in hopes of preventing UHR individuals from converting to psychosis.